Combustible DustPreventing and Mitigating the Effects of Fire

and Explosions

Developed by Western Iowa Tech Community College

This material was produced under a grant (SH-16634-07-60-F-19) from the Occupational Safety and Health Administration, U.S. Department of Labor. It does not necessarily reflect the views or policies of the U.S. Department of Labor, nor does the mention or trade names, commercial products, or organization imply endorsement by the U.S. government.

• History of combustible dust incidents• Related experience in grain handling

• Elements of a dust explosion• Dust hazard assessment

• Components• Combustibility• Electrical• Other hazards

• Dust control• Ignition control• Damage control• Training

Training Outline

Related Experience in Grain HandlingIn the late 1970’s a series of grain dust explosions in grain elevators left 59 people dead and 49 people injured.

In response to these events OSHA issued a safety and health information bulletin “Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions” (SHIB 07-31-2005) to provide employers and employees and other officials with information on the safety and health hazards associated with the storage and distribution of grain and includes all types of fibers and dust.

Explosion ofDeBruceGrainElevator

Wichita, Kansas8 June 1998

Aerial View of North Gallery, DeBruce Grain Elevator

Elements of a Dust ExplosionElements needed for a fire

1. Combustible dust (fuel)2. Ignition source (heat)3. Oxygen in air (oxidizer)

Additional elements needed for a Combustible Dust Explosion4. Dispersion of dust particles in

sufficient quantity and concentration

5. Confinement of the dust cloud

•Materials that can be combustible when finely divided;

•Dust Combustibility•Processes which use, consume, or produce combustible dusts;

•Open areas where combustible dusts may build up;

•Hidden areas where combustible dusts may accumulate;

•Means by which dust may be dispersed in the air; and

•Potential ignition sources

Facility Analysis Components

Electrical Classification

•The facility analysis must identify areas requiring special electrical equipment classification due to the presence (or potential presence) of combustible dust

Facility Analysis Components

Other Hazard Analysis Considerations

• The amount of dust accumulation necessary to cause an explosive concentration can vary greatly. This is because there are so many variables

• The particle size of the dust• The particle size of the dust• Ventilation system modes• Ventilation system modes• Physical barriers• The volume of the area in which the dust cloud exists or may exist

Facility Analysis Components

Dust ControlWhat can be done for dust control?

Ignition ControlWhat can be done to control ignition

sources?

Damage Control

What can be done for damage control?

TrainingWorkers are the first line of defense in preventing and mitigating fires and explosions. If the people closest to the source of the hazard are trained to recognize and prevent hazards associated with combustible dust in the plant, they can be instrumental in recognizing unsafe conditions, taking preventative action, and/or alerting management.

Management

What is managements duty?